Could someone with a little more experience than me please confirm my understanding, as I have not seen many of these in the field.

I have heard that some systems, particularly older systems, tee in the bathroom rad into the primary circuit. Is this done simply by teeing into the primary flow after the pump, but before zones, as per the image? In addition to this, is the return piped correctly, as per the image? If so, I am guessing the bathroom rad is simply acting as a large by-pass valve...

Bathroom slightly spoiled by white pushfit connector under WC cistern IMO. Picky or what lol? But very nice, and I do have a soft spot for panelling.
Re. the original question, yes, sounds about right. If that's how it's plumbed, with the return tees and flow tees not in the same order, then there is a risk of gravity circulation up the central heating return pipe, depending on the precise layout of the pipework (symptom would be a slight warmth in CH radiators). But if it works, then it's fine.
I think having the bathroom radiator on its own circuit as you have is a very good idea: in spring and autumn it can very often be too cold for the bathroom when the rest of the house is at a perfectly acceptable temperature.

Yeah, thought as much, but thank you for confirming. I'd never tried it as I had been told it wouldn't work/had read technical literature (and, probably, because I've never had occasion to put speedfit onto chrome). A bathroom installer, not trained as a plumber told me it wouldn't work, and I assumed that he'd found out the hard way.

Yes , lol . Those pushfit connectors are the dogs pal , far better than a fibre washer that could last one week or twenty years .

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Or fifty? When I wasn't qualified or working as a plumber, I reused a tap connector onto a new-secondhand FOV in a house I had lived in for 21 years. Unaware that the red bit was replaceable, I left the original washer in place. The washer was already at least 20 years old, and had, quite possibly, been in place since the house was built 49 years prior (in 1962) to my re-using the part. Or would you assume that the washer MUST have been replaced at some point? I'm assuming it may have sprung a trace weep at some point and then furred up.

The tap connector was originally connected to a BRE Garston type valve (an early incarnation of the Part 2). Sadly, the cistern was asbestos cement and, not wanting to disturb fibres, the original FOV was disposed of with the cistern itself.

Epilogue: the house was sold 3 years later, still with the secondhand washer in place and no evidence of leakage.

Yeah, thought as much, but thank you for confirming. I'd never tried it as I had been told it wouldn't work/had read technical literature (and, probably, because I've never had occasion to put speedfit onto chrome). A bathroom installer, not trained as a plumber told me it wouldn't work, and I assumed that he'd found out the hard way.

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1 of the 3 lengths of chrome tube did this. The other bit ok, it was a test to see how they held. Needless to say the one slip was enough to persuade me!!!

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